1. Field of the Invention
The invention concerns a process for breaking stabilized emulsions, especially oil-water emulsions, and a device for operating this process.
2. Description of the Prior Art
Classic water deoiling processes become inefficient when they are applied to certain types of emulsions that are called stabilized, especially for an oil-in-water emulsion.
Such an emulsion is constituted by a suspension in which the colloidal substance is liquid. The diameter of the oily particles is smaller than 100.mu. and often even than 60.mu..
A stable emulsion comprises fine droplets of hydrocarbons in suspension in a liquid, water in general, the viscosity of which is opposed to their agglomeration.
The forming of emulsions is favored by products currently used in Exploration/Production, such as bactericides, corrosion inhibitors, . . . that lower the interfacial tension between liquid-liquid.
The stability of a hydrocarbon emulsion in water is due especially to the equilibrium of the following forces or factors:
the forces of gravity acting on the micelles; PA1 the affinity of the micelles for the solvent; PA1 the forces of electrostatic repulsion; PA1 the solubility of the hydrocarbon in water, if aromatics, asphaltenes, . . . are present.
The micelles in suspension in water are generally negatively charged. As a result of this, a double electric layer is produced that is established at the oil-water interface.
This double layer is constituted by the charged particles and an equivalent of opposite charge ions accumulated in the water at the surface of the oily particle.
Flottation processes and coalescent filters are both generally ineffectual.
The use of an electric field was proposed by electroflottation means. In this case, the electrodes cover the surface area of the flottation basin. Through electrolysis of water, H.sub.2 and O.sub.2 microbubbles are formed that carry along the hydrocarbons towards the surface. In certain cases, the corrosion of an aluminium anode liberates Al.sub.3 +ions that act as coagulation agent.
These treatments necessitate large installations and water treatment yields hardly reach 50%.